Influence of physical development on start and countermovement jump performance in adolescent sprint athletes.

Aim: The aim of the present study was to describe the effect of physical changes during adolescence on sprint start and countermovement jump (CMJ) performance.

Methods: Twenty-eight girls and 25 boys (15.0±1.

Decrease in postural sway and trunk stiffness during cognitive dual-task in nonspecific chronic low back pain patients, performance compared to healthy control subjects.

Study Design: A 2-group experimental design.

Objective: To investigate the effect of a cognitive dual-task on postural sway of pelvis and trunk during unstable sitting in nonspecific chronic patients with low back pain (CLBP) compared to healthy control subjects.

Summary Of Background Data: Higher cognitive systems as well as sensory processes contribute to postural control.

Experimentally generated footprints in sand: Analysis and consequences for the interpretation of fossil and forensic footprints.

Fossilized footprints contain information about the dynamics of gait, but their interpretation is difficult, as they are the combined result of foot anatomy, gait dynamics, and substrate properties. We explore how footprints are generated in modern humans. Sixteen healthy subjects walked on a solid surface and in a layer of fine-grained sand.

Differences in balance strategies between nonspecific chronic low back pain patients and healthy control subjects during unstable sitting.

Study Design: A 2-group experimental design.

Objective: To investigate differences in postural control strategies of pelvis and trunk movement between nonspecific chronic low back pain (CLBP) patients and healthy control subjects using 3-dimensional motion analysis.

Summary Of Background Data: Increased postural sway assessed by center of pressure displacements have been documented in patients with low back pain (LBP).

Reliability and discriminative validity of sudden ankle inversion measurements in patients with chronic ankle instability.

Background: Studies investigating peroneal muscle reaction times in chronically unstable ankle joints present conflicting results. The degree of reliability and accuracy of these measurements is unknown in patients with chronic ankle instability (CAI).

Methods: 40 patients with CAI and 30 healthy subjects were tested using a sudden ankle inversion of 50 degrees while standing on a trapdoor device.

Test-retest reliability of sudden ankle inversion measurements in subjects with healthy ankle joints.

Context: Sudden ankle inversion tests have been used to investigate whether the onset of peroneal muscle activity is delayed in patients with chronically unstable ankle joints. Before interpreting test results of latency times in patients with chronic ankle instability and healthy subjects, the reliability of these measures must be first demonstrated.

Objective: To investigate the test-retest reliability of variables measured during a sudden ankle inversion movement in standing subjects with healthy ankle joints.

Reproducibility of postural control measurement during unstable sitting in low back pain patients.

Background: Postural control tests like standing and sitting stabilometry are widely used to evaluate neuromuscular control related to trunk balance in low back pain patients. Chronic low back pain patients have lesser postural control compared to healthy subjects. Few studies have assessed the reproducibility of the centre of pressure deviations and to our knowledge no studies have investigated the reproducibility of three-dimensional kinematics of postural control tests in a low back pain population.

Effects of hallux limitus on plantar foot pressure and foot kinematics during walking.

The effects of hallux limitus on plantar foot pressure and foot kinematics have received limited attention in the literature. Therefore, a study was conducted to assess the effects of limited first metatarsophalangeal joint mobility on plantar foot pressure. It was equally important to identify detection criteria based on plantar pressures and metatarsophalangeal joint kinematics, enabling differentiation between subjects affected by hallux limitus and people with normal hallux function.

Electron delocalization and aromaticity in linear polyacenes: atoms in molecules multicenter delocalization index.

Molecular aromaticity in the linear polyacenes is investigated using an atoms in molecules based six center index (SCI-AIM) which measures the electron delocalization. SCI-AIM values for the linear polyacenes indicate decreasing aromaticity going from outer to inner rings in the polyacene series. The SCI-AIM approach is compared to a Mulliken-like approach, and a critical comparison to the PDI index is made.

Effects of simulated genu valgum and genu varum on ground reaction forces and subtalar joint function during gait.

The mechanical effects of genu valgum and varum deformities on the subtalar joint were investigated. First, a theoretical model of the forces within the foot and lower extremity during relaxed bipedal stance was developed predicting the rotational effect on the subtalar joint due to genu valgum and varum deformities. Second, a kinetic gait study was performed involving 15 subjects who walked with simulated genu valgum and genu varum over a force plate and a plantar pressure mat to determine the changes in the ground reaction force vector within the frontal plane and the changes in the center-of-pressure location on the plantar foot.

Changes in plantar foot pressure with in-shoe varus or valgus wedging.

Varus and valgus wedging are commonly used by podiatric physicians in therapy with custom-made foot orthoses. This study aimed to provide scientific evidence of the effects on plantar foot pressure of applying in-shoe forefoot or rearfoot wedging. The plantar foot pressure distribution of 23 subjects walking on a treadmill was recorded using a pressure insole system for seven different wedging conditions, ranging from 3 degrees valgus to 6 degrees varus for the forefoot and from 4 degrees valgus to 8 degrees varus for the rearfoot.

Peroneal Reaction Times and Eversion Motor Response in Healthy and Unstable Ankles.

OBJECTIVE: To measure and compare latency, electromechanical delay, and speed of motor response of the peroneus longus muscle in a large sample of subjects with healthy or unstable ankles. DESIGN AND SETTING: Subjects with healthy or unstable ankles underwent identical test procedures consisting of 6 consecutive, sudden 50 degrees ankle-inversion movements in the standing position with full weight on the tested leg. Latency, first and second decelerations, and total inversion time were monitored.

Reliability and accuracy of biomechanical measurements of the lower extremities.

The reliability of biomechanical measurements of the lower extremities, as they are commonly used in podiatric practice, was quantified by means of intraclass correlation coefficients (ICCs). This was done not only to evaluate interrater and intrarater reliability but also to provide an estimate for the accuracy of the measurements. The measurement protocol involved 30 asymptomatic subjects and five raters of varying experience.

Control of acceleration during sudden ankle supination in people with unstable ankles.

Study Design: Comparative study of differences in functional control during ankle supination in the standing position in matched stable and unstable ankles (ex post facto design).

Objectives: To document acceleration and deceleration during ankle supination in the standing position and to determine differences in control of supination perturbation between stable and unstable ankles.

Background: Repetitive ankle sprain can be explained by mechanical instability only in a minority of cases.

Electrodynographic evaluation of the foot during treadmill versus overground locomotion.

Biomechanical foot function as expressed by the duration of successive ground contact phases and by dynamic variables, such as the peak pressure on different parts of the foot, their respective loading rate, and duration, is compared for two walking and running conditions: overground on a 20-m walkway and on a treadmill. Statistical analysis revealed foot pressure characteristics as measured with a Electrodynogram during walking and running to alter significantly when using a treadmill. The differences were more pronounced for walking than for running.

Force analysis of the rowing stroke employing two differing oar grips.

The velocity of the rowing boat appears to depend on the force which the athlete applies at the handle of the oar. Although force is generated by legs, upper body, and arms, the latter are the only limbs which actually transmit and apply the force against the oar. The force output of the arms seem to be a function of the forearm position used by the athlete while gripping the oar.